http: fix many problems with url parsing and auth. added proxy test. problems fixed: - https scheme handled properly for real and proxy urls. - url of form "http://user:password@host:port/path" now ok. - no-proxy check uses proper host names.

http: print better error if exception happens.

add ui.print_exc(), make all traceback printing central.

merge with crew.

new extension: extdiff. allows to use external diff program.

merge with crew.

diff: allow to use -rA:B syntax as well as -rA -rB

add 'uisetup' function to extension module protocol. if uisetup functin exists in extension, is called before cmdtable examined. called with ui object as parameter. lets module modify cmdtable before commands.py sees it.

notify: add debug output. do not fail if no config file. use --debug to see debug output.

hgweb.manifest: revno of manifest and changelog aren't always the same In the v4l-dvb repo, the manifest revno and the changelog revno are not in sync. This happened because the same patch was applied to the same revision in two different branches, resulting in the same manifest text, with the same parents and so the first revision was reused. Since hgweb.manifest was assuming the revnos of the manifest and of the changelog were always the same, clicking on manifest -> bz2 in the v4l-dvb site would download the wrong revision. Use the linkrev to go from manifest revision to changelog revision. This still won't be perfect since the page will still talk about "manifest for changeset XYZ", where XYZ was the first changeset to have this manifest, which is not necessarily the same changeset that the user clicked to get to this page - but at least the contents will be the same.